Manual tool for de-burring tube ends

ABSTRACT

A manually operated tool for deburring cut ends of metallic electrical tubing (EMT) and/or copper water service tubing comprising a cutting head having a pilot cylinder to fit inside the end of the tube, and a single cutting blade contoured to scrape burrs simultaneously off the inside and outside of the tube end. The cutting head is rotatably driven by a ratcheting handle having a large diameter grip radially adjustable to be positioned as pistol grip style. The deburring tool is capable of working tube ends in close quarters. 
     The large pistol grip and ratchet action combine to operate with a reduced amount of repeated motion and do not require the tight grip of a screw driver type handle. The tool is light weight and portable in contrast to prior art deburring tools requiring a drill motor for power. 
     The pistol grip encourages the use of the larger muscles of the arm instead of the hand and wrist to provide the rotating power. Also in contrast to the more common screw driver type handle, the hand and thumb are not continually flexed by the need to loosen the grip on a screw driver to reset for the next rotating operation.

RELATED APPLICATION

None

GOVERNMENT INTEREST IN THE INVENTION

None

BACKGROUND OF THE INVENTION

1. Field of the Invention

Manually operated deburring tool for internal and external deburring of the cut ends of electrical metallic conduit and/or copper water service tubing.

2. Description of Related Art

The act of cutting tubing, particularly by sawing, leaves sharp burrs on both the interior and exterior edges of tubing. For both electrical metallic conduit and copper water piping, external burrs interfere with installing the close fitting couplings used in each trade. Internal burrs in electrical conduit can cut large strips of insulation off wires as they are pulled through the conduit tubes. At minimum, a burr may pierce the insulation and cause a short circuit to the metal tube. Modern plastic coated wire is particularly sensitive to damage. The insulation is thin, and can be sliced and/or torn easily. The thinner varieties such as THHN, THWN, and MTW, while relatively tough, have insulation that is only a few thousandths of an inch thick

Searching the US patent files suggests that tube end dressing is a crowded art. However, of the 150 patents reviewed, most were substantial machines, and most of those that are described as “portable” used motorized power, generally a drill motor.

Electricians working on building construction encounter several conditions that are not adequately addressed by the prior art. Many common tool characteristics described in the prior art simply do not work well in most of the identified problem areas, and none were found that address all the characteristic problems found at job sites.

It is not uncommon that a conduit has to be cut off after being mounted in the building. This is usually done with a hack saw which leaves burrs inside and outside over only part of the tube end, more importantly, the cut end is rarely at right angles to the tube axis. Only a small number of reaming tool configurations will adequately deburr angled cuts, and they have inherent defects in functioning well. Conical reams having small cone angles typical of that shown in U.S. Pat. No. 3,976,388 by George Webb, have several deficiencies when used on angled cuts or intermittent burrs. Mr. Webb's device is and inside-outside reamer. Because the cutters are arranged in a circle, it will have difficulty with angled and wavy cuts. Conical reams having a cone angle of 60 to 90 degrees for inside deburring will work better than Webb's small angle reams because they can be slightly offset from the tube axis, but the cutting pressure is distributed around the tube in a manner that may cause over cutting on the side opposite a heavy burr.

Arrow cutters typically have only two cutting edges working on opposite ends of the tube diameter. Arrow cutters with an angle of between 60 and 90 degrees work well on perpendicular cut tubes and can work adequately on slightly angular and wavy cut ends, they also have a tendency to gouge the tube wall opposite a tough burr.

Another condition often confronting an electrician is where the tube has been mounted close to a wall. The usual mounting brackets may place the tube as close a ⅜ of an inch. If the central axis of an angular cut is tilted toward the wall, the tools just described cannot be tilted to fit the angled face of the tube.

A single cutter tool such as shown in U.S. Pat. Nos. 6,487,947 and 6,524,035 will follow the contour of the tube end while operating coaxially with the tube axis. Both of these patents teach an identical cutting head driven by a drill motor.

It is obvious that when the tube needing deburring is mounted that closely to an interfering wall, there is no room to use a drill motor to power the cutter, and that presumes that a source of electricity is readily available. The same is true for a manual tool with a screwdriver like handle. The hand on the driver handle, like a drill motor, takes up too much room. Webb's T handle also requires significant space for rotation. Close mounting of conduit tubes requires a deburring tool that has a turning axis that is coaxial with the tubing axis and can follow the contour of a cut tubing end and can be used in such close quarters. The present invention is designed for just that use.

The clearance of tubes mounted closely to obstructions is common enough to be a criteria for consideration in tool design. Most work is more in the open but occasionally tubes ready for deburring are stacked on a rack or similar where the clearance between tubes is negligible. This situation requires a reamer that can reach into the uneven end of the stack and does not take significantly more space than the outer diameter of the tubes. Of course, some of the tubes will have to be pulled axially from the stack end or others pushed back to gain adequate access to the tube end under consideration.

Screwdriver shaped handles require a tight grip for turning and a loosened grip to re-set for the next twist. This places repeated stress on the thumb, hand, and wrist. With such repeated use, the hand fatigues and may result in carpel tunnel injury. T handles put large transverse loads on the base of the thumb in addition to pure torsional stress on the wrist. Again this causes excess fatigue and may induce carpel tunnel injury.

The present invention is designed to prevent repeated stressing on the thumb, hand, and wrist that cause injury to the hand or wrist.

3. Objects of the Invention

It is an object of the invention to provide a tool for deburring cut ends of tubing without subjecting the thumb, hand, and wrist to severe repetitive stresses and flexing.

It is another object of the invention the tool be operable when the tubing being deburred is attached to walls and the like where little space is available for working the tool.

It is another object of the invention that the tool deburr tubing where the cut end may not be square with the tube axis, and may even be non-planar.

It is another object of the invention that the tool be manually powered.

It is another object of the invention that the tool be carry able on a tool belt or in a workman's pocket.

It is another object of the invention that the tool require only one hand to operate.

It is another object of the invention that the tool be usable on a ladder or man lift, reaching overhead, or reaching into a hole, or other awkwardly accessible locations.

BRIEF SUMMARY OF THE INVENTION

A manually operated tool for deburring cut ends of electrical metallic tubing (EMT) and/or copper water service tubing comprising a cutting head having a pilot cylinder to fit inside the end of the tube, and a single cutting blade contoured to scrape burrs simultaneously off the inside and outside of the tube end. The cutting head is rotatably driven by a ratcheting handle having a large diameter grip that is radially offset and adjustable to be positioned into a pistol grip style. The deburring tool is capable of working tube ends in close quarters.

The large pistol grip and ratchet action combine to operate with a reduced amount of repetitive motion and do not require the tight hand grip of a screw driver type handle. The tool is light weight and portable in contrast to prior art deburring tools requiring a drill motor for power.

The pistol grip encourages the use of the larger muscles of the arm instead of the hand and wrist to provide the rotating power. Also in contrast to the more common screw driver type handle, the hand and thumb are not continually flexed by the need to loosen the grip as with a screw driver to reset for the next rotational operation.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an isometric view of the tool.

FIG. 2 is an arrow point reaming cutter.

FIG. 3 is a conical point reaming cutter.

TABLE OF IDENTIFIED DETAILS

-   -   1. The complete tube reaming tool.     -   2. The preferred cutting head.     -   3. The preferred ratcheting handle assembly     -   4. Pilot guide fitting inside the tubing being deburred     -   5. Deburring cutter     -   6. Driven end of ratchet     -   7. Handle end of ratchet     -   8. Handle Grip     -   9. Ratchet control     -   10. Handle pivot and lock     -   11. Bit adapter     -   12. Drive shank     -   13. Body of arrow style cutter     -   14. Cutting edge of arrow style cutter     -   15. Driving shank of arrow and/or cone cutter     -   16. Body of cone style cutter     -   17. Cutting edges of cone style cutter

DETAILED DESCRIPTION OF THE INVENTION

A tool for deburring the cut ends of electrical metallic tubing (EMT) comprising a cutting head turned by a hand held ratcheting handle having a grip being transversely adjustable relative to the rotating axis of the cutting head is described.

Referring to FIG. 1, the tool is identified as item 1. The cutting head portion is identified as 2, and the overall ratcheting handle is identified as 3. The cutting head 2 is adapted to deburr at least one standard size of electrical tubing by inserting a pilot cylinder 4 into the tube for centering and stabilizing the rotation of the cutter 5. In the preferred embodiment, the cutter 5 has 2 functional knife edges for simultaneously deburring both the inside and outside rims of the tube end. It is preferred that the pilot cylinder have only one cutter tool so that it can follow the contour of the cut edge and uneven burr patterns. Burrs from saw cutting tend to be primarily on one side of the circular cut. The inside and outside burrs tend to be on opposite sides of the end cut edge. Furthermore, often the tube must be cut using a hack saw in awkward locations such as after being mounted in the building under construction or hand held on a sawhorse. This can result in angled cuts and non-circular cuts. Worse, the last small portion of the cutting process is often accompanied by the tare end of the tube bending and breaking away from the main portion of the tube, thus leaving a particularly heavy burr and/or axial projection requiring extra care to remove. A deburring tool having more than one cutting edge limits the tool's effectiveness to flat, perpendicular cuts and relatively even burr patterns.

The preferred cutting head 2 has three pilots 4, each having a compatible inside-outside cutting bit 5. Each pilot and cutter is adapted to deburr a standard size of tubing. A cutting head having the described characteristics is available from Klein Tools as model number 19352, and is described in U.S. Pat. No. 6,487,947. Klein Tools are widely distributed through tool supply outlets.

Two patents were found that describe using the Klein tool. Both teach that it the tool is to be powered by a drill motor. The present invention teaches that the preferred driving power be the operator's arm muscles. Again referring to FIG. 1, the handle assembly 3 has two parts critical to the success of the deburring tool. First, the handle is equipped with a ratchet mechanism between the driven end 6 and the driving end 7, so that hand/arm power is provided in a series of oscillating motions without having to release the grip on the handle. Second, the overall handle 3 has a comfortable, enlarged offset gripping portion 8, which can be offset to be similar to a pistol grip form. The pistol grip design permits the hand and wrist to be in a more comfortable position and encourages using the larger muscles of the forearm and upper arm to turn the tool, thereby relieving the hand and thumb from having to perform strong repetitive motions. The pistol grip has an advantage over a straight screwdriver form handle in that it requires less, actually zero, clearance between the tool and any obstructions behind a mounted tube. No need for clearance space for either handle or hand. An handle offset between 40 and 80 degrees, with a mid range setting usually being the best, permits the operator's arm to apply force parallel to the tubing axis without extra wrist strain. The user can set the offset to the amount found to be most effective for cutting and/or least fatiguing, or varied to provide relief from tiring use. It is important that the tool be usable with only one hand, the other hand may be needed for bodily support while working on a ladder or raised platform.

The tool from the cutting head to the pivot for the handle should all be within a dimensioned space no larger in diameter than the cutting assembly. Preferably, the tool diameter should taper away to smaller than the just described space

A suitable handle by Central Forge Brand is available from Harbor Freight Catalog #46801-1VGA. This handle has the required functionality plus several other features useful for a tool like that being described. This handle has a lock-left-right selector 9 for the ratchet operation. The hand grip portion 8 pivots at 10 relative to the axial barrel 7 so the handle may be used as a straight screwdriver type or adjustably offset up to approximately 80 degrees. The handle pivot is equipped with a lock/release mechanism to permit adjustment and to be securely locked at the selected position. The Central Forge handle also has an adapter 11 for receiving a set of screwdriver bits and/or wrench style nut driver sockets. This permits the present tool to be used to fasten hardware such as tubing clamps, terminal screws, etc without having to carry separate tools.

The ratcheting handle shank 12 is slightly larger than the central bore of the Klein deburring head, therefore, the Klein deburring head has to be drilled out to be adapted to the Central Forge handle. This does not reduce the functionality of either part or of the overall tool.

ALTERNATIVE EMBODIMENTS AND VARIATIONS OF THE INVENTION

The preferred ratcheting drive assembly can be replaced with a conventional ratchet drive from a socket set. This alternative is not as satisfactory as the preferred drive with the angled offset handle because the 90 degree handle cannot be used to provide axial force to the cutter without considerable wrist strain. To effectively use a conventional socket set drive, two hands must be used. One to turn the ratcheting handle and the other to provide axial force to the cutting head.

The preferred cutter assembly has only one cutter which can follow the contour of the cut end of a tube. A cone or arrow cutter (see FIGS. 2 and 3) may work for some jobs, but will work poorly or not at all if the tube end is not square and the burrs are tot reasonably small and uniform. A typical arrow type deburring cutter is described in U.S. Pat. No. 3,763,510, by Joseph Graham and illustrated in FIG. 2. A flat body 13 is fitted with a means to rotate it, usually a cylindrical extension coaxial with the body and pointed portion. The pointed portion has angled edges that scrape the work to remove burrs. In the context of this disclosure, the operations of scraping and cutting are equal and synonymous. Cone or arrow cutters should have a point angle of 45 to 90 degrees, preferably approximately 60 degrees. The cone cutter may be simply described as an array of cutting edges or scrapers 17 arranged symmetrically in a cone shape around an axis like a common countersinking tool. The usual, but not necessarily so, cone cutter has a cylindrical body 18 with an axial cylindrical extension 15 for rotating the tool.

Separate cutting tools for deburring the inside and outside of the tube is an option. Obviously, this requires a tool or tools with cutters adapted for each edge.

While the deburring tool has been described for use on thin wall EMT and copper water tubing, it can easily be adapted to work on various schedules of plastic varieties of electrical and water tubing.

How to Use the Invention

The described tool is inserted into the end of a length of electrical metallic tubing or similar copper water supply tubing; the cutter is forced axially against the tube end; then rotated by back and forth motion of the operator's hand and/or arm. The ratchet mechanism permits the cutter to be forced to travel in one direction around the tube end rim. The burrs are scraped off and the tube is left with a smoothly machined end ready for joining with another length of tubing or with a tube end fitting.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to falling within the scope of the invention as defined by the claims which follow.

The embodiments of the invention in which an exclusive property right or privilege is claimed are defined as follows: 

1. A method of deburring cut ends of a tube comprising the steps of: a. inserting a deburring tool into the end of a tube to be deburred; where said deburring tool has an axis of rotation, at least one cutting edge adapted to revolve around said axis of rotation and remove burrs from the end of the tube, a handle for manually applying power to the tool, ratcheting means between said handle and said cutting edge to convert an oscillating rotational motion of the handle to a uni-directional rotational motion of the cutting edge, and a centering means for aligning the axis of rotation of the tool to the axis of the tube; and b. setting a ratcheting means to operably restrict the motion of the cutting edge to a single direction of rotation; and c. applying pressure aligned coaxially with the axis of the tube and simultaneously applying rotary oscillating motion to the handle, thereby causing the cutting edge to traverse the end of the tube and dislodge any burrs clinging there on.
 2. The steps of claim 1 further comprising setting said handle to an position offset from said axis of rotation between 40 and 80 degrees, thereby orienting the handle for comfortable use when applying axial and rotational forces.
 3. A tool for deburring cut ends of tubing comprising in combination: a. a tool having an axis of rotation, a cutting blade adapted to deburr the end of a tube, a handle adapted to receive power from the user's muscles, a ratcheting means between said cutting blade and said handle for converting oscillatory rotational motion of the handle into uni-directional rotation of the cutting blade; and b. a tool body co-axial with said axis of rotation, said body comprising first and second elongated portions each having distal and proximal ends and aligned coaxially with said axis of rotation, a shank attached in coaxial alignment to the distal end of said first elongated portion, a ratcheting means operatively joining the proximal end of the first elongated portion with the distal end of the second elongated portion, where said ratcheting means converts oscillatory rotational motion of the second elongated portion into uni-directional rotational motion of the second elongated portion; and c. and a handle attached to the distal end of the second elongated portion, said handle being offset 40 to 80 degrees transversely from said axis of rotation; and d. a cutting blade holding means coaxially attached to said shank, said cutter assembly comprising a cylindrical body, receiving means for receiving the cutting blade, and at least one alignment means comprising a coaxially aligned cylindrical portion adapted to be received within the end of a tube and to cause the cutter assembly to be rotably coaxially aligned with the axis of said tube, e. whereby, when said alignment means is inserted into the end of a tube, and axial force and oscillatory rotational force are simultaneously applied to said handle, said cutter means traverses the end of said tube and removes burrs present on the rim of said tube.
 4. The tool of claim 3, where said handle is pivotally attached to said second ratable portion of the body of the tool, where the range of pivot ability is 40 to 80 degrees from the axis of the tool body, and said pivotally attachment further comprises a locking mechanism to releasably fix the degree of offset while the tool is in use.
 5. The tool of claim 3 where the coaxial body of said tool is entirely within a cylindrical space defined by the locus of the cutting blade as it rotably traverses a tube end and is extended axially from said cutting blade.
 6. The tool of claim 3 where the offset handle permits the tool to be rotated with the wrist in coaxial alignment with the forearm thereby reducing strain on the wrist and thumb.
 7. The tool of claim 3 where the offset handle permits the tool to be rotably powered by the muscles of the user's upper arm and shoulder thereby reducing strain on the muscles of the thumb, wrist, and forearm. 